The invention relates to a method and a device in autoclaves, comprising a container which is divided into imaginary areas, which are heated by the feeding of steam into the areas in order to heat goods which have been placed in the autoclave so that said goods reach sterilising temperature.
For a long time, these kinds of autoclaves have been used when sterilising newly manufactured products which have to be sterilised before being put on the market. Infusion solutions, such as glucose or blood plasma, or vitamins and proteins in solid or liquid state are examples of such products.
After completed manufacture of a product of any of the above mentioned kinds, the product is loaded as goods onto carriages, the carriages being placed in one area each in the autoclave, said autoclave will subsequently be closed, and steam will be fed into each area in order to sterilise the goods.
The products are manufactured according to the market demand, usually in very different quantities depending on the product. A problem in this connection is that the demand for a product might be so small that within a certain time one is able to fill one carriage only, whilst the autoclave is dimensioned for several carriages. Disregarding this fact and leaving one or several areas in the autoclave empty during the sterilising process is however, most disadvantageous. Steam which is fed into the empty area/areas will flow to the cool goods on the carriage and consequently the outermost goods will become more rapidly heated than the goods placed in the centre. Said goods may be of a nature that does not allow exposure to too high temperatures during too long periods. This would happen in the above mentioned case where the duration of the sterilising process is determined by a measuring probe which is placed at the centre of the carriage. For thermolabile goods, such as sugar solutions (glucose), the reaching of high temperatures at too early a stage would lead to caramelization, which in turn would lead to the goods having to be discarded. Thus, development of the sterilising process is achieved only when the interplay between heat and time is correct.
Nor is it advisable to choose an alternative arrangement where, after having loaded goods for sterilisation onto a carriage, the sterilisation of a product is postponed until sufficient quantities have been produced to fill the autoclave with carriages containing the same kind of sterilising goods. Several kinds of products are so sensitive that they have to be discarded if they are not sterilised within a few hours of the manufacturing.
By means of the invention, a method, by which the above described problem can be solved has been provided by regulating the feeding of steam and consequently the feeding of heat into the different areas of the autoclave. The method is characterised in that upon registration in one area of a temperature which by a predetermined number of degrees exceeds the simultaneously registered temperature level in another area, preferably the adjacent area, the feeding of steam to the first-mentioned area will be interrupted and upon registration of a temperature in the same area which equals the level of, or is close to the level of said other or adjacent area, steam will again be fed to the first-mentioned area.
The characteristic features of the device for carrying out the method according to the invention are described in the appended claim 2.